Upgrade to Slim 3 - how to change request & parameters?

I am upgrading from v2 to v3. Unfortunately, it has been years that I implemented the code, and I am not very much used to the API configuration.

The URL looks like this

https://URL/api/variables_gegslive_new/find/gel13

and the v2 code like this:

$app->get('/variables_gegslive_new/find/:query', function ($query) use ($app)

How does this translates into Slim v3? This seems to be not working properly:

$app->get('/variables_gegslive_new/{find}/{id}', function ($request, $response, $args) 
{
	echo "iii";
	echo  $request;
	include ("file.php");
}

Strangely enough, if I delete the line “echo $request” the function “$app->…” is not being called, or at least, run through.

Thanks for any help!

Perhaps the logic that is embedded in the file file.php prevents the processing of the request.